Guide
JPG vers WebP vs PNG vers WebP : quelles différences ?
Comprenez pourquoi les conversions JPG→WebP et PNG→WebP ne donnent pas les mêmes résultats.
Le format source influence fortement le rendu final. JPG et PNG ne réagissent pas de la même façon en WebP.
JPG and PNG start from different data
JPG is already lossy, so converting it to WebP usually gives incremental savings rather than dramatic quality improvements.
PNG is often lossless or transparency-heavy, so converting to WebP can reduce size a lot, but settings must be chosen carefully.
What to expect from JPG to WebP
For photo content, WebP often cuts size further while keeping acceptable quality.
If the original JPG is already heavily compressed, pushing quality too low can quickly look worse.
What to expect from PNG to WebP
UI graphics and transparent assets can shrink significantly with WebP.
But text edges and logos need closer review, especially with lossy settings.
- Keep transparency checks in your QA step.
- Use higher quality for text-heavy graphics.
- Use lossless mode for critical brand assets.
Build two simple conversion rules
Use one default for photos (usually lossy) and another for graphics/transparency (often lossless or higher quality).
This keeps automation simple and avoids quality surprises.
Useful when
- Planning bulk conversion jobs.
- Comparing before/after image weight.
- Choosing export rules by asset type.
Start from the source format
If you separate JPG and PNG workflows, your WebP results become more predictable and easier to control.